Make plan that has vertex that match the grid
I think I figured it out. When he does the first 2 extrusions, the only way I was able to do the same was to select the 2 vertices, then hit "e", but left click before dragging. This seems to make it an edge or a cut or something. After that, leaving whatever was already selected, selected, I hit "e" again and then drag it out. I did that on both sides.

This left the vertices that he clicks on the side. However, here you had to do the same thing. Hit "e", left click to finalize the extrusion, then hit "e" again and then drag it out. This allowed it to come out at 90 degree angles. Otherwise it kept it all connected.  

After that, he went to object mode, hit "a", then w->s to subdivide it into equal squares. 

Thanks for the help.